There is a considerable demand in industry for large-area solid-state light sources for a number of applications, predominantly in the area of display elements, display screen technology and illumination technology. The requirements made of these light sources can currently not be met entirely satisfactorily by any of the existing technologies.
As an alternative to conventional display and illumination elements, such as incandescent lamps, gas-discharge lamps and non-self-illuminating liquid-crystal display elements, electroluminescent (EL) materials and devices, such as light-emitting diodes (LEDs), have already been in use for some time.
Besides inorganic electroluminescent materials and devices, low-molecular-weight, organic electroluminescent materials and devices have also been known for about 30 years (see, for example, U.S. Pat. No. 3,172,862). Until recently, however, the practical utility of such devices was greatly restricted.
EP 423 283 and EP 443 861 describe electroluminescent devices which contain a film of a conjugated polymer as light-emitting layer (semiconductor layer). Such devices have numerous advantages, such as the possibility of producing large-area, flexible displays simply and inexpensively. In contrast to liquid-crystal displays, electroluminescent displays are self-illuminating and therefore do not require an additional back-lighting source.
A typical device in accordance with EP 423 283 consists of a light-emitting layer in the form of a thin, dense polymer film (semiconductor layer) which contains at least one conjugated polymer. A first contact layer is in contact with a first surface, and a second contact layer is in contact with a further surface of the semiconductor layer. The polymer film of the semiconductor layer has a sufficiently low concentration of extrinsic charge carriers so that, on application of an electric field between the two contact layers, charge carriers are introduced into the semiconductor layer, where one contact layer becomes positive compared with the other, and the semiconductor layer emits radiation. The polymers used in devices of this type are referred to as conjugated. The term xe2x80x9cconjugated polymerxe2x80x9d is taken to mean a polymer which has a delocalized electron system along the main chain. The delocalized electron system gives the polymer semiconductor properties and enables it to transport positive and/or negative charge carriers with high mobility.
EP 423 283 and EP 443 861 describe, as polymeric material for the light-emitting layer, poly(p-phenylenevinylene), which may be modified on the aromatic ring by alkyl, alkoxy, halogen or nitro substituents in order to improve the properties. Polymers of this type have since then been investigated in a large number of studies, and bisalkoxy-substituted PPVs in particular have already been optimized a very long way toward applicational maturity (cf., for example, J. Salbeck, Ber. Bunsenges. Phys. Chem. 1996, 100, 1667).
The German patent application 196 52 261.7 with the title xe2x80x9cAryl-substituted poly(p-arylenevinylenes), process for their preparation, and their use in electroluminescent componentsxe2x80x9d, which was not published before the priority date of the present application, proposes aryl-substituted poly(p-arylenevinylenes) which are also suitable for generating green electroluminescence.
However, the development of polymers of this type can in no way be regarded as complete, and there continues to be plenty of room for improvement. Thus, inter alia, improvements are still possible with respect to the service life and stability, in particular at elevated temperatures.
The object of the present invention was therefore to provide electroluminescent materials which, when used in illumination or display devices, are suitable for improving the property profile of these devices.
Surprisingly, it has now been found that poly(arylphenylenevinylenes) whose phenylene unit carries a further substituent in the para- or meta-position to the aryl radical are particularly suitable as electroluminescent materials.
The invention therefore relates to poly(arylenevinylenes) comprising at least 20% of recurring units of the formula (I), 
where the symbols and indices have the following meanings:
Aryl: is an aryl group having 4 to 14 carbon atoms;
Rxe2x80x2: is a substituent which is either in the labeled phenylene position 5 or 6 and is CN, F, Cl, N(R1R2) or a straight-chain, branched or cyclic alkyl, alkoxy or thioalkoxy group having 1 to 20 carbon atoms, in which, in addition, one or more H atoms may be replaced by F;
Rxe2x80x3: are identical or different and are CN, F, Cl or a straight-chain, branched or cyclic alkyl or alkoxy group having 1 to 20 carbon atoms, where one or more non-adjacent CH2 groups may be replaced by xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, xe2x80x94NR1xe2x80x94, xe2x80x94(NR2R3)+-Axe2x88x92 or xe2x80x94CONR4xe2x80x94, and where one or more H atoms may be replaced by F, or an aryl group having 4 to 14 carbon atoms, which may be substituted by one or more non-aromatic radicals Rxe2x80x2;
R1, R2, R3, R4 are identical or different and are H or an aliphatic or aromatic hydrocarbon radical having 1 to 20 carbon atoms;
Axe2x88x92: is a singly charged anion or an equivalent thereof; and
n: is 0, 1, 2, 3, 4 or 5.
The polymers according to the invention are highly suitable for use as electroluminescent materials. They have, for example, the advantage of having constant brightness in long-term operation, even at elevated temperatures (for example heating for a number of hours at 85xc2x0 C.).
It is thus not necessary to adjust the voltage during long-term operation in order to obtain an initial brightness. This advantage is particularly evident in the case of battery operation, since the maximum voltage economically possible is greatly restricted here.
Devices containing the polymers according to the invention also have a long service life.
Surprisingly, the polymers according to the invention have a particularly low content of defect structures.
The polymers generally contain from 10 to 10,000, preferably from 10 to 5000, particularly preferably from 100 to 500, very particularly preferably from 250 to 2000, recurring units.
Polymers according to the invention comprise at least 20%, preferably at least 30%, particularly preferably at least 40%, of recurring units of the formula (I).
Furthermore, preference is also given to copolymers consisting of recurring units of the formula (I) and recurring units containing a 2,5-dialkoxy-1,4-phenylenevinylene structure. Preference is likewise given to copolymers consisting of recurring units of the formula (I) and recurring units containing a 2-aryl-1,4-arylenevinylene structure which is not further substituted.
Preference is furthermore given to copolymers comprising 1, 2 or 3 different recurring units of the formula (I).
For the purposes of the present invention, the term xe2x80x9ccopolymersxe2x80x9d covers random, alternating, regular and block-like structures.
Preference is also given to polymers comprising recurring units of the formula (I) in which the symbols and indices have the following meanings:
Aryl is phenyl, 1- or 2-naphthyl, 1-, 2- or 9-anthracenyl, 2-, 3- or 4-pyridinyl, 2-, 4- or 5-pyrimidinyl, 2-pyrazinyl, 3- or 4-pyridazinyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-quinolinyl, 2- or 3-thiophenyl, 2- or 3-pyrrolyl, 2- or 3-furanyl or 2-(1,3,4-oxadiazol)yl;
Rxe2x80x2 are identical or different and are CN, F, Cl, CF3 or a straight-chain or branched alkoxy group having 1 to 12 carbon atoms;
Rxe2x80x3 are identical or different and are a straight-chain or branched alkyl or alkoxy group having 1 to 12 carbon atoms; and
n is 0, 1, 2 or 3, particularly preferably 0, 1 or 2.
Particular preference is given to polymers in which the aryl substituent in the formula (I) has the following meaning: phenyl, 1-naphthyl, 2-naphthyl or 9-anthracenyl.
Particular preference is furthermore given to polymers in which the aryl substituent in the formula (I) has the following substitution pattern: 2-, 3- or 4-alkyl(oxy)phenyl, 2,3-, 2,4-, 2,5-, 2,6-, 3,4- or 3,5-dialkyl(oxy)phenyl, 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6- or 3,4,5-trialkyl(oxy)phenyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-alkyl(oxy)-1-naphthyl, 1-, 3-, 4-, 5-, 6-, 7- or 8-alkyl(oxy)-2-naphthyl or 10-alkyl(oxy)-9-anthracenyl.
The polymers according to the invention can be obtained, for example, by dehydrohalogenation polymerization from starting materials of the formula (II) in which the symbols and indices are as defined under the formula (I), and Hal and Halxe2x80x2 are Cl, Br or I; this is generally carried out by reacting one or more monomers with a suitable base in a suitable solvent. 
These monomersxe2x80x94with the exception of 2,5-bis(chloromethyl)4-methoxy-4xe2x80x2-(3,7-dimethyloctyloxy)biphenyl and 2,5-bis(chloromethyl)4-methoxy-3xe2x80x2-(3,7-dimethyloctyloxy)biphenyl, both of which were disclosed in WO 98/25874xe2x80x94are novel and are therefore likewise a subject-matter of this invention.
To this end, the monomers are dissolved in suitable solvents in suitable concentrations, brought to the suitable reaction temperature and mixed with the suitable amount of a suitable base. After a suitable reaction time has passed, the reaction solution can be terminated, for example by addition of acid. The polymer is subsequently purified by suitable methods familiar to the person skilled in the art, such as, for example, reprecipitation or extraction.
Examples of suitable solvents are ethers (for example diethyl ether, THF, dioxane, dioxolane and tert-butyl methyl ether), aromatic hydrocarbons (for example toluene, xylenes, anisole and methylnaphthalenes), alcohols (for example ethanol and tert-butanol), chlorinated compounds (for example chlorobenzene and dichlorobenzene) and mixtures of these solvents.
A suitable concentration range is the range from 0.005 to 5 mol/l (monomer/solution volume). Preference is given here to the range from 0.01 to 2 mol/l, very particularly preferably to the range from 0.01 to 0.5 mol/l.
The reaction temperature is generally from xe2x88x9280 to 200xc2x0 C., preferably from 20 to 140xc2x0 C.
Examples of suitable bases are alkali metal hydroxides (NaOH and KOH), hydrides (NaH and KH) and alkoxides (NaOEt, KOEt, NaOMe, KOMe and KOtBu), organometallic compounds (nBuLi, sBuLi, tBuLi and PhLi) and organic amines (LDA, DBU, DMAP and pyridine). A suitable amount is in the range from 2 to 10 equivalents (based on one equivalent of monomer), preferably from 3.5 to 8 equivalents, particularly preferably from 4 to 6 equivalents.
The reaction time is generally from 5 minutes to 24 hours, preferably from 0.5 to 6 hours, very particularly preferably from 1 to 4 hours.
This process is likewise a subject-matter of the invention.
The biaryl derivatives indicated in the formula (II) can be obtained by the route outlined in Scheme 1:
The starting compounds of the formulae (III) and (IV) are very readily accessible since they can be prepared in a simple manner and in large amounts from commercially available compounds. 
The reactions in Scheme 2 can be explained as follows: the 1,4-dimethyl compound (VI) is generally commercially available (for example 2,5-dimethylphenol, 2,5-dimethylaniline, 2,5-dimethylbenzonitrile or 2,5-dimethylanisole) or can be prepared simply from commercially available compounds (for example alkylation of a corresponding phenol or amine). The compound (VI) can be halogenated, for example chlorinated or brominated, on the aromatic ring by standard methods (see, for example, Organikum [Synthetic Organic Chemistry], VEB Deutscher Verlag der Wissenschaften, 15th Edition, pp. 391 ff., Leipzig 1984). The resultant compounds (VII) are accessible in good yields and in industrial quantities. Analogously, the compounds of the type (VIxe2x80x2) are also either commercially available or can be prepared easily (for example 2,5-dibromo-p-xylene). These compounds can then likewise be converted into compounds of the type (VII) by standard reactions (for example nucleophilic substitution of a halogen by an alkoxy radical). (VII) can be converted, preferably catalytically (cobalt catalyst, atmospheric oxygen, see, for example, EP-A 0 121 684) into the corresponding 1,4-dicarboxylic acids (IIIa). Given a suitable choice of the reaction conditions, this is possible irrespective of the substituent. The resultant acids, (IIIa) with R=H, can, if desired, be converted into the corresponding esters (Rxe2x89xa0H) by standard methods.
The compounds of the formula (IIIa), which are obtained virtually quantitatively in this way, can be converted into the bisalcohols (IIIb) by conventional reduction reactions. These bisalcohols are also obtainable directly from the compounds of the formula (VII) by oxidation (see, for example, A. Belli et al., Synthesis 1980, 477).
It may also prove advantageous to delay conversion of the substituent (Pxe2x80x2) into the substituent (Rxe2x80x2) until the stage of the carboxylic acid or its ester, i.e. to delay carrying out reaction (1xe2x80x2) until this point: This is principally appropriate in the case of long-chain alkoxy substituents, since these would otherwise possibly be destroyed by air oxidation.
The halogen atom can, if desired, be replaced by a boric acid, borate or trialkyltin group at a suitable stage, as described below for the compounds of the formula (IVa).
The corresponding perfluoroalkylsulfonates can be prepared, for example, by esterification of corresponding phenol functions. 
Scheme 3 can be explained as follows: the compounds (VIII) are generally commercially available (for example diverse alkyl- and dialkylaromatic compounds or alkoxyaromatic compounds) or can be prepared simply from corresponding precursors (for example hydroquinone, pyrocatechol, naphthol and the like), for example by alkylation. The compound (VIII) can then be converted into compounds of the formula (IVa) by simple halogenation reactions (Reaction 5), as described above. Many compounds of the formula (IV) are inexpensive chemicals (for example bromophenol and bromoaniline) which can be converted simply into compounds of the formula (IVa) by Reaction 6 (for example alkylation of phenyl functions). These compounds of the formula (IVa) can then be metallated by corresponding reagents (for example Mg turnings, n-BuLi or s-BuLi) and then converted into the corresponding compounds of the formula (IVb) or (IVc) by corresponding further reaction, for example with trialkyltin chloride or trialkyl borate.
It can thus be seen that the starting compounds (III) and (IV) are accessible in a simple manner in the requisite range of variations. The starting compounds (III) and (IV) are converted into intermediates of the formula (V) by a coupling reaction (Reaction A in Scheme 1).
To this end, the compounds of the formulae (III) and (IV) are reacted in an inert solvent at a temperature in the range from 0xc2x0 C. to 200xc2x0 C. in the presence of a palladium catalyst.
In each case one of these compounds, preferably the compound of the formula (III), contains a halogen or perfluoroalkylsulfonate group and the other contains a boric acid or borate group (IVb) or a trialkyltin group (IVc).
In order to carry out the above reaction A with boric acids or borates of the formula (IVb), Variant Aa, Suzuki coupling, the aromatic boron compound, the aromatic halogen compound or the perfluoroalkylsulfonate, a base and catalytic amounts of the palladium catalyst are added to water or to one or more inert organic solvents or preferably to a mixture of water and one or more inert organic solvents and stirred at a temperature of from 0 to 200xc2x0 C., preferably from 30 to 170xc2x0 C., particularly preferably from 50 to 150xc2x0 C., especially preferably from 60 to 120xc2x0 C., for a period of from 1 hour to 100 hours, preferably from 5 hours to 70 hours, particularly preferably from 5 hours to 50 hours. The crude product can be purified by methods known to the person skilled in the art and appropriate for the respective product, for example by recrystallization, distillation, sublimation, zone melting, melt crystallization or chromatography.
Examples of organic solvents which are suitable for the process described are ethers, for example diethyl ether, dimethoxyethane, diethylene glycol dimethyl ether, tetrahydrofuran, dioxane, dioxolane, diisopropyl ether and tert-butyl methyl ether, hydrocarbons, for example hexane, isohexane, heptane, cyclohexane, toluene and xylene, alcohols, for example methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, 1-butanol, 2-butanol and tert-butanol, ketones, for example acetone, ethyl methyl ketone and isobutyl methyl ketone, amides, for example dimethylformamide, dimethylacetamide and N-methylpyrrolidone, and nitrites, for example acetonitrile, propionitrile and butyronitrile, and mixtures thereof.
Preferred organic solvents are ethers, such as dimethoxyethane, diethylene glycol dimethyl ether, tetrahydrofuran, dioxane and diisopropyl ether, hydrocarbons, such as hexane, heptane, cyclohexane, toluene and xylene, alcohols, such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol and ethylene glycol, ketones, such as ethyl methyl ketone and isobutyl methyl ketone, amides, such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone, and mixtures thereof.
Particularly preferred solvents are ethers, for example dimethoxyethane and tetrahydrofuran, hydrocarbons, for example cyclohexane, toluene and xylene, alcohols, for example ethanol, 1-propanol, 2-propanol, 1-butanol and tert-butanol, and mixtures thereof.
In a particularly preferred variant, water and one or more water-insoluble solvents are employed in the process described. Examples are mixtures of water and toluene and water, toluene and tetrahydrofuran.
Bases which are preferably used in the process described are alkali and alkaline earth metal hydroxides, alkali and alkaline earth metal carbonates, alkali metal hydrogencarbonates, alkali and alkaline earth metal acetates, alkali and alkaline earth metal alkoxides, and primary, secondary and tertiary amines.
Particular preference is given to alkali and alkaline earth metal hydroxides, alkali and alkaline earth metal carbonates and alkali metal hydrogencarbonates.
Particular preference is given to alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide, and alkali metal carbonates and alkali metal hydrogencarbonates, such as lithium carbonate, sodium carbonate and potassium carbonate.
The base is preferably employed in the above process in a proportion of from 100 to 1000 mol %, particularly preferably from 100 to 500 mol %, very particularly preferably from 150 to 400 mol %, especially from 180 to 250 mol %, based on the aromatic boron compound.
The palladium catalyst contains palladium metal or a palladium(O) or palladium(II) compound and a complex ligand, preferably a phosphine ligand.
The two components can form a compound, for example the particularly preferred Pd(PPh3)4, or can be employed separately.
Examples of suitable palladium components are palladium compounds, such as palladium ketonates, palladium acetylacetonates, nitrilopalladium halides, olefinpalladium halides, palladium halides, allylpalladium halides and palladium biscarboxylates, preferably palladium ketonates, palladium acetylacetonates, bis-xcex72-olefinpalladium dihalides, palladium(II) halides, xcex73-allylpalladium halide dimers and palladium biscarboxylates, very particularly preferably bis(dibenzylideneacetone)palladium(O) [Pd(dba)2)], Pd(dba)2 CHCl3, palladium bisacetylacetonate, bis(benzonitrile)palladium dichloride, PdCl2, Na2PdCl4, dichlorobis(dimethylsulfoxide)palladium(II), bis(acetonitrile)palladium dichloride, palladium(II) acetate, palladium(II) propionate, palladium(II) butanoate and (1c,5c-cyclooctadiene)palladium dichloride.
The catalyst can also be palladium in metallic form, referred to below as simply palladium, preferably palladium in powdered form or on a support material, for example palladium on activated carbon, palladium on aluminum oxide, palladium on barium carbonate, palladium on barium sulfate, palladium on aluminum silicates, such as montmorillonite, palladium on SiO2 and palladium on calcium carbonate, in each case with a palladium content of from 0.5 to 10% by weight. Particular preference is given to palladium in powdered form, palladium on activated carbon, palladium on barium and/or calcium carbonate and palladium on barium sulfate, in each case with a palladium content of from 0.5 to 10% by weight. Particular preference is given to palladium on activated carbon with a palladium content of 5 or 10% by weight.
The palladium catalyst is employed in the process according to the invention in a proportion of from 0.01 to 10 mol %, preferably from 0.05 to 5 mol %, particularly preferably from 0.1 to 3 mol %, especially preferably from 0.1 to 1.5 mol %, based on the aromatic halogen compound or the perfluoroalkylsulfonate.
Examples of ligands which are suitable for the process are phosphines, such as trialkylphosphines, tricycloalkylphosphines and triarylphosphines, where the three substituents on the phosphorus may be identical or different, chiral or achiral, and where one or more of the ligands can link the phosphorus groups from a plurality of phosphines, and where part of this link may also be one or more metal atoms.
Examples of phosphines which can be used in the process described here are trimethylphosphine, tributylphosphine, tricyclohexylphosphine, triphenylphosphine, trisolylphosphine, tris(o-tolyl)phosphine, tris(4-dimethylaminophenyl)phosphine, bis(diphenylphosphano)methane, 1,2-bis(diphenylphosphano)ethane, 1,3-bis(diphenylphosphano)propane and 1,1xe2x80x2-bis(diphenylphosphano)ferrocene. Examples of other suitable ligands are diketones, for example acetylacetone and octafluoroacetylacetone, and tertiary amines, for example trimethylamine, triethylamine, tri-n-propylamine and triisopropylamine. Preferred ligands are phosphines and diketones, particularly preferably phosphines. Very particularly preferred ligands are triphenylphosphine, 1,2-bis(diphenylphosphano)ethane, 1,3-bis(diphenylphosphano)propane and 1,1xe2x80x2-bis(diphenylphosphano)ferrocene, in particular triphenylphospine.
Also suitable for the process are water-soluble ligands containing, for example, sulfonic acid salt and/or sulfonic acid radicals and/or carboxylic acid salt and/or carboxylic acid radicals and/or phosphonic acid salt and/or phosphonic acid radicals and/or phosphonium groups and/or peralkylammonium groups and/or hydroxyl groups and/or polyether groups of suitable chain length.
Preferred classes of water-soluble ligands are phosphines substituted by the above groups, such as trialkylphosphines, tricycloalkylphosphines, triarylphosphines, dialkylarylphosphines, alkyldiarylphosphines and heteroarylphosphines, such as tripyridylphosphine and trifurylphosphine, where the three substituents on the phosphorus may be identical or different, chiral or achiral, and where one or more of the ligands can link the phosphorus groups from a plurality of phosphines, and where part of this link may also be one or more metal atoms, phosphites, phosphinites and phosphonites, phosphols, dibenzophosphols and cyclic- and oligo- and polycyclic compounds containing phosphorus atoms.
The ligand is employed in the process in a proportion of from 0.1 to 20 mol %, preferably from 0.2 to 15 mol %, particularly preferably from 0.5 to 10 mol %, especially preferably from 1 to 6 mol %, based on the aromatic halogen compound or the perfluoroalkylsulfonate. It is also possible, if desired, to employ mixtures of two or more different ligands.
All or some of the boronic acid derivative employed can be in the form of the anhydride.
Advantageous embodiments of the variant Aa process described are described, for example, in WO 94/101 05, EP-A-679 619, WO-A-694 530 and PCT/EP 96/03154, which are expressly incorporated herein by way of reference.
In variant Ab, also known as the Stille coupling, an aromatic tin compound, preferably of the formula (IVc), is reacted with an aromatic halogen compound or an aromatic perfluoroalkylsulfonate, preferably of the formula (III), at a temperature in the range from 0xc2x0 C. to 200xc2x0 C. in an inert organic solvent in the presence of a palladium catalyst.
A review of this reaction is given, for example, in J. K. Stille, Angew. Chemie Int. Ed. Engl. 1986, 25, 508.
In order to carry out the process, the aromatic tin compound [lacuna] the aromatic halogen compound or the perfluoroalkylsulfonate are preferably introduced into one or more inert organic solvents and stirred at a temperature of from 0xc2x0 C. to 200xc2x0 C., preferably from 30xc2x0 C. to 170xc2x0 C., particularly preferably from 50xc2x0 C. to 150xc2x0 C., especially preferably from 60xc2x0 C. to 120xc2x0 C., for a period of from 1 hour to 100 hours, preferably from 5 hours to 70 hours, particularly preferably from 5 hours to 50 hours. When the reaction is complete, the Pd catalyst obtained as a solid is separated off, for example by filtration, and the crude product is freed from solvent or solvents. Further purification can subsequently be carried out by methods known to the person skilled in the art and appropriate for the respective product, for example by recrystallization, distillation, sublimation, zone melting, melt crystallization or chromatography.
Examples of organic solvents which are suitable for the process described are ethers, for example diethyl ether, dimethoxyethane, diethylene glycol dimethyl ether, tetrahydrofuran, dioxane, dioxolane, diisopropyl ether and tert-butyl methyl ether, hydrocarbon, for example hexane, isohexane, heptane, cyclohexane, benzene, toluene and xylene, alcohols, for example methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, 1-butanol, 2-butanol and tert-butanol, ketones, for example acetone, ethyl methyl ketone and isobutyl methyl ketones, amides, for example dimethylformamide (DMF), dimethylacetamide and N-methylpyrrolidone, and nitriles, for example acetonitrile, propionitrile and butyronitrile, and mixtures thereof.
Preferred organic solvents are ethers, such as dimethoxyethane, diethylene glycol dimethyl ether, tetrahydrofuran, dioxane and diisopropyl ether, hydrocarbons, such as hexane, heptane, cyclohexane, benzene, toluene and xylene, alcohols, such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol and ethylene glycol, ketones, such as ethyl methyl ketone, or amides, such as DMF.
Particularly preferred solvents are amides, very particularly preferably DMF.
The palladium catalyst contains palladium metal or a palladium(O) or palladium(II) compound and a complex ligand, preferably a phosphine ligand.
The two components can form a compound, for example Pd(PPh3)4, or can be employed separately.
Examples of suitable palladium components are palladium compounds, such as palladium ketonates, palladium acetylacetonates, nitrilopalladium halides, olefinpalladium halides, palladium halides, allylpalladium halides and palladium biscarboxylates, preferably palladium ketonates, palladium acetylacetonates, bis-xcex72-olefinpalladium dihalides, palladium(II) halides, xcex73-allylpalladium halide dimers and palladium biscarboxylates, very particularly preferably bis(dibenzylideneacetone)palladium(O) [Pd(dba)2)], Pd(dba)2 CHCl3, palladium bisacetylacetonate, bis(benzonitrile)palladium dichloride, PdCl2, Na2PdCl4, dichlorobis(dimethylsulfoxide)palladium(II), bis(acetonitrile)palladium dichloride, palladium(II) acetate, palladium(II) propionate, palladium(II) butanoate and (1c,5c-cyclooctadiene)palladium dichloride.
The palladium catalyst is employed in the process described in a proportion of from 0.01 to 10 mol %, preferably from 0.05 to 5 mol %, particularly preferably from 0.1 to 3 mol %, especially preferably from 0.1 to 1.5 mol %, based on the aromatic halogen compound or the perfluoroalkylsulfonates.
Examples of ligands which are suitable for the process described are phosphines, such as trialkylphosphines, tricycloalkylphosphines and triarylphosphines, where the three substituents on the phosphorus may be identical or different, chiral or achiral, and where one or more of the ligands can link the phosphorus groups from a plurality of phosphines, and where part of this link may also be one or more metal atoms.
The ligand is employed in the process described in a proportion of from 0.1 to 20 mol %, preferably from 0.2 to 15 mol %, particularly preferably from 0.5 to 10 mol %, especially preferably from 1 to 6 mol %, based on the aromatic halogen compound or the perfluoroalkylsulfonate.
Reaction B
If the group Xxe2x80x2 in the intermediate (V) is xe2x80x94COOR, it is reduced to the bisalcohol, Xxe2x80x2=CH2OH.
The reduction can be carried out by known methods familiar to the person skilled in the art, as described, for example, in Houben-Weyl, 4th Edn. Vol. 6, 16, Chapter VIII, Georg-Thieme-Verlag, Stuttgart 1984.
Preferred embodiments are the following:
a) Reaction with LiAlH4 or diisobutylaluminum hydride (DIBAL-H) in tetrahydrofuran (THF) or toluene, as described, for example, in Organikum [Synthetic Organic Chemistry] (see above), pp. 612 ff.
b) Reaction with boron hydrides, such as BH3, as described, for example, in Houben-Weyl, 4th Edn. Vol. 6, 16, Chapter VIII, pp. 211-219, Georg-Thieme-Veriag, Stuttgart 1984.
c) Reaction with hydrogen in the presence of a catalyst, as described, for example, in Houben-Weyl, 4th Edn. Vol. 6, 16, Chapter VIII, pp. 110 ff., Georg-Thieme-Verlag, Stuttgart 1984.
d) Reaction with sodium or sodium hydride.
Particular preference is given to reduction using LiAlH4 or DIBAL-H.
Reaction C
In accordance with the invention, the OH groups in the bisalcohols of the formula (V) can be replaced by halogen by nucleophilic substitution.
In order to prepare chlorides and bromides, it is preferred to react the corresponding bisalcohol with HCl or HBr, for example in glacial acetic acid (see, for example, Houben-Weyl, Volume 5/4, pp. 385 ff., 1960) or with thionyl chloride or bromide, if desired in the presence of a catalyst (see, for example, Houben-Weyl, Volume 5/1b, pp. 862 ff., 1962). Chlorides can also preferably be prepared by reaction with phosgene (see, for example, Houben-Weyl, Volume V, 3, pp. 952 ff, 1962) or with BCl3, and bromides by reaction with PBr3.
Iodides can preferably be prepared by reaction with phosphorus/iodine by the method of A. I. Vogel (see, for example, Houben-Weyl, Volume V, 4, pp. 615 ff., 1969).
Alternatively, the halides can be interchanged in a comparable manner to the FINKELSTEIN reaction; thus, monomers containing two different halides, or mixtures thereof, can also advantageously be employed. The work-up is carried out in all cases in a simple manner by known methods familiar to a person skilled in the art.
The synthetic methods described here enable, for example, the preparation of the following monomers which can be converted into polymers according to the invention. 
Key: C4: 2-methylpropyl; C8: 2-ethylhexyl; C10: 3,7-dimethyloctyl.
Polymers comprising recurring units of the formula (I) can be prepared from the monomers of the formula (II) accessible in this way by the polymerization variant indicated abovexe2x80x94if desired with addition of further comonomers. Comonomers of this type are, for example, the compounds shown below. 
Key: C4: 2-methylpropyl; C8: 2-ethylhexyl; C10: 3,7-dimethyloctyl.
The homopolymers or copolymers according to the invention produced in this way are very particularly suitable as electroluminescent materials. For the purposes of the present invention, the term xe2x80x9celectroluminescent materialsxe2x80x9d is taken to mean materials which can be used as an active layer in an electroluminescent device. The term xe2x80x9cactive layerxe2x80x9d means that the layer is capable of emitting light (light-emitting layer) on application of an electric field and/or that it improves the injection and/or transport of the positive and/or negative charges (charge injection or charge transport layer).
The invention therefore also relates to the use of a polymer comprising at least 20% of recurring units of the formula (I) in an electroluminescent device, in particular as electroluminescent material.
In order to be used as electroluminescent materials, the polymers comprising structural units of the formula (I) are generally applied in the form of a film to a substrate by known methods familiar to the person skilled in the art, such as dipping or spin coating.
The invention thus likewise relates to an electroluminescent device having one or more active layers, where at least one of these active layers comprises one or more polymers according to the invention. The active layer can be, for example, a light-emitting layer and/or a transport layer and/or a charge-injection layer.
The general construction of electroluminescent devices of this type is described, for example, in U.S. Pat. No. 4,539,507 and U.S. Pat. No. 5,151,629. Electroluminescent devices containing polymers are described, for example, in WO-A 90/13148 and EP-A 0 443 861.
They usually contain an electroluminescent layer between a negative electrode and a positive electrode, where at least one of the electrodes is transparent. In addition, one or more electron-injection and/or electron-transport layers can be introduced between the electroluminescent layer and the negative electrode and/or one or more hole-injection and/or hole-transport layers can be introduced between the electroluminescent layer and the positive electrode. Suitable negative electrodes are preferably metals or metal alloys, for example Ca, Mg, Al, In or Mg/Ag. The positive electrodes can be metals, for example Au, or other metallically conducting substances, such as oxides, for example ITO (indium oxide/tin oxide) on a transparent substrate, for example made of glass or a transparent polymer.
In operation, the negative electrode is set to a negative potential compared with the positive electrode. Electrons are injected by the negative electrode into the electron-injection layered-electron-transport layer or directly into the light-emitting layer. At the same time, holes are injected by the positive electrode into the hole-injection layer/hole-transport layer or directly into the light-emitting layer.
The injected charge carriers move through the active layers toward one another under the effect of the applied voltage. This results in electron/hole pairs recombining at the interface between the charge-transport layer and the light-emitting layer or within the light-emitting layer with emission of light.
The color of the emitted light can be varied by means of the materials used as light-emitting layer.
Electroluminescent devices are used, for example, as self-illuminating display elements, such as control lamps, alphanumeric displays, signs and in opto-electronic couplers.
The invention is explained in greater detail by the examples which follow, without this being intended to represent a limitation.
Part 1: Synthesis of the Monomers
A. Synthesis of Compounds of the Formula (III)